NetBSD Problem Report #54498

From  Wed Aug 28 11:24:20 2019
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Date: Wed, 28 Aug 2019 13:24:10 +0200 (CEST)
Subject: instant + total VFS deadlock
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>Number:         54498
>Category:       kern
>Synopsis:       instant + total VFS deadlock
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Aug 28 11:25:00 +0000 2019
>Last-Modified:  Fri Aug 30 12:30:01 +0000 2019
>Originator:     Martin Husemann
>Release:        NetBSD 9.99.10
The NetBSD Foundation, Inc.
System: NetBSD 9.99.10 NetBSD 9.99.10 (GENERIC) #302: Mon Aug 26 09:04:19 CEST 2019 amd64
Architecture: x86_64
Machine: amd64

Stupid mistake, don't try this at home kits:

 1) create a new GPT partition somewhere (type ffs), let's say the wedge gets
    called dk2
 2) newfs -O2 /dev/rdk2
 2) mount /dev/dk2 /mnt
    (first mistake here: forgot to specify async or log)
 3) cd $somewhere; pax -rw -pe . /mnt
 4) while pax is still running, notice the slow transfer and try to add async:
    mount -u -o async /dev/dk2 /mnt
    (in another terminal)

Watch all disk activity die, mount -u never proceeding (unstoppable), system
still reacts to ping and existing process carry on, but all disk access seems
to block.



From: "J. Hannken-Illjes" <>
Subject: Re: kern/54498: instant + total VFS deadlock
Date: Fri, 30 Aug 2019 11:32:54 +0200

 Cannot reproduce it here.  Next time it happens please run

 call fstrans_dump(1)

 from DDB.

 J. Hannken-Illjes - - TU Braunschweig (Germany)

From: Martin Husemann <>
Subject: Re: kern/54498: instant + total VFS deadlock
Date: Fri, 30 Aug 2019 14:26:06 +0200

 Hmm, I can not reproduce it either now.

 The initial occurance was with booting single user from wd0,
 new partition on wd3 (or something like that, both on the same ahcisata
 controller), and source of the copy from external disk (sd0, via USB<->sata
 connector) mounted read-only.

 Maybe it needs full speed sata write transfers and there is a race?
 Or only happens with read-only / ?


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